The invention relates to an exhaust gas system for an internal combustion engine.
Such an exhaust gas flow control system for an internal combustion engine, in particular of a motor vehicle, is known from DE 10 2008 064 264 A1. The exhaust gas system comprises a first exhaust gas duct as well as a second exhaust gas duct which is at least partially fluidically separated from the first exhaust gas duct. Exhaust gas from the internal combustion engine can flow through each of the exhaust gas ducts. Furthermore, the first exhaust gas duct is associated with a first turbine duct of a turbine of an exhaust gas turbocharger. The second exhaust gas duct is associated with a second turbine duct of the turbine which is at least partially fluidically separated from the first turbine duct. This means that exhaust gas is or can be delivered to the first turbine duct via the first exhaust gas duct, whilst exhaust gas from the internal combustion engine is or can be delivered to the second turbine duct via the second exhaust gas duct.
The exhaust gas flow control system further comprises an exhaust gas return line which branches off from the first exhaust gas duct. To this end, the exhaust gas return line is connected fluidically to the first exhaust gas duct at a branch point of the first exhaust gas duct, so that, at the branch point, exhaust gas from the first exhaust gas duct can be diverted into the exhaust gas return line. The exhaust gas return line serves for returning exhaust gas from the internal combustion engine to an inlet side of the latter, in order thus to be able to achieve low-emission operation of the internal combustion engine.
Finally, the exhaust gas flow control system comprises a shut-off element. The shut-off element is adjustable between at least one closed position, which prevents exhaust gas from flowing out of the first exhaust gas duct into the exhaust gas return line, and at least one open position, which allows exhaust gas to flow out of the first exhaust gas duct into the exhaust gas return line. In other words, in the at least one closed position the exhaust gas return line is fluidically shut off, so that exhaust gas does not flow through the exhaust gas return line. In the open position, the exhaust gas return line is fluidically opened, so that exhaust gas flows through the exhaust gas return line.
An exhaust gas system for an internal combustion engine is also known from DE 10 2005 021 172 A1. The exhaust gas from a defined number of cylinders of the internal combustion engine flows through a first exhaust gas duct. The exhaust gas from the remaining cylinders of the internal combustion engine flows through a second exhaust gas duct. A bypass line is provided between the first exhaust gas duct and the second exhaust gas duct. The exhaust gas ducts can be fluidically connected to one another by means of the bypass. A first shut-off element, by means of which the bypass line can be fluidically opened and shut off, is disposed in the bypass line. Furthermore, the exhaust gas system has an exhaust gas return line which branches off from the first exhaust gas duct and has a second shut-off element. The exhaust gas return line can be fluidically opened and shut off by the second shut-off element. Finally, the first exhaust gas duct has a third shut-off element downstream of the exhaust gas return line. The first exhaust gas duct can be fluidically opened and shut off by the third shut-off element. This exhaust gas system has a relatively high degree of complexity. Furthermore, in the conventional exhaust gas systems it has proved difficult and particularly costly to be able to achieve high engine braking performance of the internal combustion engine.
It is the object of the present invention to provide an exhaust gas flow control system of the type referred to above in such a way that, by means of the exhaust gas system, it is also possible to achieve high engine braking performance in a particularly uncomplicated manner.